Now you get to be paid to fly! This is a major step in your aviation career. When people know you are a 'Commercial' pilot, then they know you exhibit the highest levels of skill, safety and professionalism.
To obtain a commercial certificate you should have your Instrument Rating first. Although you CAN get a commercial certificate without an instrument rating, you will be serverly limited in what you may legally do as a commercial pilot.
You can plan on two weeks to obtain your commercial certificate. We will cover advanced commercial flight maneuvers, FAR's pertaining to commercial operations, High Altitude operations and more.
You are not a new pilot anymore and your CFI should take that into consideration. Expect to dive right into the advanced maneuvers and regulations. As with any flight instruction, taking the self initiative in studying ahead of time will help tremendously. Be familier with AC 120-12A, FAR Part 61 pertaining to Commercial Pilot Requirements and understand the purpose of FAR Part 119, 121 & 135.
You should have an Instrument Rating for this training.
Before beginning your training go out and practice a bit. Remember that the standards are much more stringent in your commercial checkride. Are you a coordination master? Locked up on that altitudes? You can be a hard critic to yourself.
The commercial training is far less time consuming than the private training, but it does require the use of a complex aircraft, which results in a higher plane rental cost. Please review the tips I give in the Private Course and apply them here as a means to keep your costs at a very minimum. Be prepared, be ready and keep the training compressed are the best ways to minimize needless expense.